1. Field of the Invention
The present invention relates generally to agricultural seeders that produce open furrows in the soil into which seeds are placed, and more particularly, to an improved seed-directing tube and boot, and method of attaching and operating the tube and boot for use with such seeders in obtaining improved seed placement in the furrows.
2. Description of the Related Art
Agricultural planting methods continue to advance in response to widespread adoption of “no-till” or “reduced-till” crop production techniques with greatly reduced dependence on tillage of the soil, and in which the next crop's seeds are often placed directly into the previous crop's stubble or crop residues. No-till or reduced-till seeding differs greatly from seeding into a tilled seedbed. Although the soil conditions for no-till seeding are typically characterized by more structural stability than tilled soils, as the soil particles are “aggregated” or held together by old roots, fungi, and other organic substances and molecular attractions binding the particles together, it is still of considerable importance to prevent loose soil and “duff” (chaff and small pieces of partially decomposed mulch) from entering the seed furrow prematurely, before the seeds have come to rest at the bottom of the furrow. This is of particular importance on single-disc opener designs which are particularly vulnerable to loose soil and duff sloughing into the furrow after the opener disc has passed, relying on soil stability and/or a seed boot to inhibit the loose soil and duff from entering the furrow until after the seeds have been adequately placed in the bottom of the cut furrow.
Single-disc opener designs for seed or fertilizer placement have met with considerable success in no-till seeding, partly due to simplicity. Because of the structural stability of no-till soils, much higher down-force requirements are imposed on the opener disc to cut the furrow to a consistent depth. This additional strain generally necessitates more robust opener discs together with a much larger hub and mechanical bearing(s) on which the opener discs are rotatably mounted, and this durability requirement also lends an advantage to the single-disc design for cost and space constraints. Larger hubs and bearings on the opener discs can interfere with the routing of seed-delivery tubes and positioning of gauge wheels.
Gauge wheels pose a design problem because the most desirable positioning is with the gauge wheel contacting the soil most forcefully at the point where the opener disc's rearward edge is rotating up out of the soil. This allows the gauge wheel to control “sidewall blowout,” which results from the opener disc's upward rotation and angle to the direction of travel causing the furrow sidewall to tear apart and lift upward, i.e., following the disc's rotation upward as it exits the furrow. When left unchecked, sidewall blowout sometimes results in the furrow sidewall tearing completely free and being flung out of the furrow by the opener disc's momentum, thereby creating an irregularly shaped furrow and/or allowing pieces of the sidewall to enter the furrow before seeds have been properly placed.
The opener disc is typically mounted at a slight angle to the direction of travel so that it is pushing soil laterally to create a furrow. For controlling sidewall blowout, gauge wheels generally are mounted in the same plane as the opener discs, with the inner lip of the gauge wheel flush against the outer edge of the opener disc (“outer” refers to the side away from the furrow being cut). With a 16-inch or 18-inch diameter opener disc (the preferred disc sizes due to optimal cutting ability at 1.5- to 2-inch seeding depth; larger sizes hairpin more mulch, and smaller sizes are more prone to plugging or “bulldozing” of clumps of straw or debris), and a 15-inch gauge wheel (again, the preferred size, since smaller sizes resist rolling over small obstacles in the field, and larger sizes get in the way of other components), the forward edge of the gauge wheel is then approximately at the axis of the opener disc, which prevents the opener disc's hub from being located on the outside of the opener disc, especially if it is a large heavy-duty hub (“outside” refers to the side away from the furrow being formed). Hence, a double-disc design has somewhat limited options as to where to locate relatively large hubs, since the opener discs must be at a narrow angle to each other to cut the soil properly, with such relationship physically precluding large hubs from being between the discs. On the single-disc design, the large hubs are typically located on the opposite side of the opener disc from the gauge wheel, which is the inside of the opener disc.
With a large hub on the inside of the opener disc, the seed delivery tube must pass either ahead of the hub or behind it. If the seed tube passes in front of the hub, the trajectory of the seeds passing inside the tube will be approximately at a 45-degree angle to the furrow (in the horizontal plane of the soil when on level terrain), aimed rearward as much as downward, due to the need for the seeds to enter the furrow when it has appreciable width, which would be directly below the hub and rearward of it. The rearward seed trajectory poses a significant problem of ricochet, which is the tendency of the seeds to bounce upward and out of the furrow after striking the soil or the opener disc after the seeds exit the seed-directing tube and/or boot. While a significant problem for grain drills with gravity-fed seed delivery, this problem is greatly exacerbated by forced-air delivery which has become commonplace on larger width drills called “air drills.” The seeds are carried in an air stream and move at a velocity greater than that attained by seeds falling solely under the influence of gravity, thereby increasing the ricochet effect. Further, if no provision is made for the pressure of the air stream to be vented or diffused to the ambient atmosphere until the seeds exit the lower end of the seed tube or boot, the air stream itself can carry lighter seeds out of the furrow as the air stream blasts into the furrow and then out of the furrow as it escapes.
A single-disc no-till drill opener design that has met with great success in the marketplace is typified by the John Deere drill models 1590 and 1890, and their predecessor models 1560 and 1860 (hereinafter “Deere 60- and 90-series”), both of which are slightly updated versions of the basic opener design described in U.S. Pat. No. 4,760,806 issued to Bigbee, which was first embodied in John Deere drill models 750 and 1850 (hereinafter “Deere 50-series”). On the Deere 60- and 90-series openers, as well as the 50-series, the seed boot is held directly on the opener subframe via a single bolt, with the boot being able to pivot on the bolt's axis by a few degrees. The boot is urged toward the opener disc by a leaf spring secured in a recess below the bolt, which continually holds one side of the boot's forward/lower edge flush against the opener disc. The seed tube passes forward of the disc's hub and enters the top of the boot near the aforementioned bolt attachment point which is also ahead of the hub.
A significant downfall of the design of the John Deere 50-, 60- and 90-series drill opener assemblies is the protrusion of the boot beyond the cut made by the opener disc (not operating in the “shadow” of the opener disc). This protrusion greatly inhibits the ability of the boot to be operated deeper than with the boot's lowermost edge approximately flush with the soil surface, due to the boot being relatively blunt on its lower edge and therefore resisting penetration of firm soil. Attempts to operate the boot more deeply in relation to the soil result in higher horsepower requirements, much higher down-force requirement on the opener unit (or a tendency for the opener to “ride out” and fail to maintain depth), and substantially greater wear on the boot and its attachment point. With the boot not extending below the soil surface, the boot has very limited ability to hold loose soil and duff out of the furrow while the seeds are being placed, as well as very limited ability to compensate for the ricochet effect of seed bounce. This seed bounce problem is exacerbated by the failure of the boot to extend below the soil surface, and by the remarkable failure of the seed bounce flap to enclose the rear of the boot, being situated at a 45-degree angle from vertical and in relation to the boot such that a sizeable gap occurs at the rear corner during field operation. The flap is the essence of U.S. Pat. No. 5,092,255 issued to Long et al., termed a “seed boot extension” therein, although commonly called a seed bounce flap in the industry.
Other single-disc drill designs have routed the seed tube behind the opener disc's hub, resulting in the seed tube being more nearly vertical, and possibly angled slightly forward at the lower end. The more vertical orientation results in less seed ricochet, although it is quite important that the tube not be too far rearward in relation to the opener disc because of reduced control over seed placement, and it is also important that a boot and seed bounce flap adequately direct the seeds into the bottom of the furrow. This seed tube arrangement was integrated into a single-disc no-till opener that was marketed for several years (now discontinued) as Flexi-coil's “FSO” or “F/SO,” and is depicted in U.S. Pat. No. 6,237,696 B1 issued to Mayerle. With Mayerle '696, the seed boot (a.k.a. “scraper”) is attached directly to the seed tube, which is itself rigidly attached to the opener subframe. The boot attaches to the tube via two bolts and by compressing a thin rubberized pad between the upper end of the boot and the tube. As the boot (scraper) wears against the opener disc, the bolts must be continually readjusted to keep the forward edge of the boot against the opener disc; neglect of this adjustment often results in weeds or straw becoming lodged between the boot and the opener disc, which eventually arrests the rotation of the opener disc or causes the opener to otherwise plug with straw or debris. However, the shape and location of the Mayerle '696 boot and tube allow much greater precision in placing seeds at the bottom of the seed furrow as compared to the Deere 60- and 90-series.
U.S. Pat. No. 6,216,616 B1 issued to Bourgault depicts a single-disc opener (lacking a gauge wheel; depth is limited only by down-force applied to the disc opener and by soil resilience which varies across the field) with a scraper or boot attached directly to the opener subframe, independent of the seed tube, and with the scraper or boot being rotatably mounted and spring-tensioned against the opener disc. The design has the seed tube routed rearward of the opener disc's hub. The general design of the Bourgault '616 seed tube and scraper/boot arrangement overcomes some of the adjustment and straw plugging difficulties mentioned in the foregoing discussion of the Flexi-coil FSO (Mayerle '696). However, the Bourgault scraper/boot design is almost entirely ineffective at holding loose soil and duff out of the furrow because of the failure of the scraper/boot to extend forward into the area where the disc is actually creating the cut, failure to extend sufficiently downward into the furrow, and failure to create any sort of enclosure at the rear of the tube or scraper. Furthermore, the Bourgault design (embodied in air drills sold by Bourgault Industries Ltd.) lacks the seed-placement precision of gauge-wheel openers such as the Deere 60- and 90-series, and also lacks separation of the seed-firming function from furrow closing (and from opener depth-gauging), all of which are agronomically desirable.
Baugher et al., U.S. Pat. Nos. 5,595,130, 5,802,995, and 6,029,591, depict a single-disc opener with a tube passing rearward of the opener disc's hub, although with the boot (“runner”) attached directly to the tube. The entire boot and tube assembly pivots about a single attaching bolt or pin at the forward end of the assembly, and is biased toward the opener disc with a spring. In '995 and '130, the boot pivots about an axis that is mostly horizontal (with its axis along the direction of travel), while in '591 it pivots about an axis that is nearly vertical. While the Baugher '130, '995, and '591 patents retain most of the other functional elements of the Deere 50-, 60-, and 90-series opener, the seed boots and tubes depicted therein involve substantial revision of the opener design to accommodate the boot and tube; i.e., the boots and tubes depicted in these patents wouldn't fit existing Deere 50-, 60-, and 90-series openers, nor would any alterations allow the boots and tubes to fit those openers without a wholesale rebuilding of the opener subframe. The Baugher '130, '995, and '591 patents also depict a seed tube which is still oriented somewhat rearward and not forward at its lower end, and also with the lower end of the tube located more rearward of the disc's axis than is desirable since the disc is useful in holding the soil and duff out of the furrow while seeds are being placed, and this occurs to the greatest extent where the disc is at the bottom of the furrow (i.e.,directly below the disc axis). Furthermore, the Baugher '130, '995, and '591 patents depict seed boots without adequate enclosure of their lower rearward portions to prevent seeds from bouncing into undesirable locations, i.e., seeds not being adequately channeled into the bottom of the furrow. The prior art before Baugher also deployed seed and fertilizer boots (a.k.a. runners or shoes) with nearly identical shapes and construction, i.e, sufficiently narrow as to stay within the furrow cut by the disc. For example, such boots were used in single-disc gauge-wheel fertilizer openers sold by John Deere since the late 1980s on their row-crop planters.
Yet another type of seed boot for single-disc drill openers is described in Wendling et al., U.S. Pat. No. 6,347,594 B1, with a substantially vertical seed tube passing rearward of the opener disc's hub. The seed tube is attached directly to a narrow boot that pivots about a bolt on a horizontal axis (along the direction of travel, and parallel to the opener disc). The boot and tube are biased toward the opener disc via a leaf spring. However, the boot and tube design and attachment method constitute a major departure from the Deere 60- and 90-series openers; thus, this boot and tube arrangement envisioned by Wendling in the '594 patent could not be fitted onto those openers without a wholesale rebuilding of the opener subframe. The opener depicted in the '594 patent has trailing wheels and arms for covering or packing that are dramatically different from the Deere 50-, 60-, and 90-series' firming and closing arms, with considerably more space afforded for the boot and tube assembly described and depicted in the '594 patent. And, again, the rearward lower portion of the boot in Wendling '594 fails to create sufficient enclosure to direct the great majority of seeds into the bottom of the furrow.